Light and photocell unit for sorting apparatus



azuwvmu 5N Get. 27, 1970 w, 3,536,927

LIGHT AND PHOTOCELL UNIT FOR SORTING APPARATUS Filed Oct. 17, 1968INVENTOR. WILLIAM H MINK BY GRAY, MASE aoumsom 1 ATTORNEYS BYM Z 49m3,536,927 LIGHT AND PHOTOCELL UNIT FOR SORTING APPARATUS Wiiliam H.Mink, Columbus, Ohio, assignor to Scientific Advances, Inc, Columbus,Ohio, a corporation of Ohio Filed Oct. 17, 1968, Ser. No. 768,488 Int.Cl. B07c 5/342; G06k 9/06; H01j 39/08 US. Cl. 250-220 13 Claims ABSTRACTOF THE DISCLOSURE Light introduced at the center of a block oftransparent acrylic resin spreads throughout and is reflected back fromits smooth or coated external surfaces. A transparent opening at eachdesired area of illumination transmits lightto a test surface from whichsome of the light is reflected through a filter and to a photocell, bothmounted in the opening.

BACKGROUND OF THE INVENTION This invention comprises apparatus forproviding light of constantly proportional intensities in a plurality oflight reception areas on a test surface and for detecting lightreflected from those areas.

Such apparatus is useful for discriminating between desired andundesired documents, such as currency, as in the method and apparatus ofUnited States Patent 3,220,- 549 0f Lan I. Wong. Wongs apparatusincludes light source means emitting visible light in a plurality ofcolor sections including respective color components existing on onesurface of a desired document. The document to be inspected is held instationary relationship with respect to the light source, with thesurface of interest exposed to the source so as to receive the lighttherefrom. A plurality of light sensitive means are provided whichrespectively develop electrical signals having amplitudes responsive tothe spectral content of the light received thereby. The light sensitivemeans are disposed respectively to receive light reflected from aplurality of preselected discrete areas of the one surface of thedocument, thereby respectively to develop signals in response to thespectral characteristics of the areas. The signals are analyzed, and anindicating signal is provided when the spectral content of the lightreflected from each of the areas of the document being inspectedconforms to that of a desired document.

Wong uses a fluorescent light to illuminate selected areas of a documentthrough apertures in an opaque plate between the fluorescent light andthe document. Light reflected from the various areas is detected byphototubes and photocells mounted in separate compartments having opaquepartitions between them and the fluorescent light.

The present invention provides improved equivalent apparatus, all in onecompact solid integral unit.

SUMMARY OF THE INVENTION Typical apparatus according to this inventionfor providing light of constantly proportional intensities in aplurality of light reception areas on a test surface and for detectinglight reflected from those areas comprises in combination: a solidinternally transparent light distributor member having a face portionadjacent the test United States Patent 0 surface and comprising anillumination area in substantial registry with each light receptionarea, a recess in the light distributor member having a source of lightfixedly mounted therein, and an opening in the light distributor memberat each illumination area having a light detector positioned therein toreceive light reflected from the test surface.

The external surface of the light detector member typically issubstantially smooth over most of its area to contain the light from thesource substantially Within the member except at the illumination areas,and at least any region of abrupt change in the external surface may becoated with light reflective material to reduce the loss of light. Themember may be made of any suitable material, such as an acrylic resin orother transparent plastic. \Vhere desired, the material may be such thatit transmits light over a range of frequencies substantially narrowerthan the entire visible spectrum. The filtering action can be aninherent property of the material in its usual or natural form; or thematerial maybe treated, as by tinting, to modify its light transmissioncharacteristics.

The recess and light source typically are substantially centrallylocated among the light reception areas. Each opening typicallycomprises a cylindrical portion for holding the light detector(typically a photocell) therein and an outwardly extending conicaltransparent portion for transmitting light to the illumination area. Alight filter may be provided in the opening between the test surface andthe light detector, which preferably is isolated from all light exceptthat reflected from the adjacent light reception area on the testsurface.

The light distributor member may be made transparent over a narrowregion within the periphery of the test surface, and means may beprovided for detecting any light passing through the test surfaceadjacent the narrow region. Suitable detecting means may comprise asolid transparent light reception member (similar to the lightdistributor member) having a face portion, adjacent the test surface onthe side opposite the light distributor memher, that is transparent overa narrow region in substantial registry with the narrow transparentregion of the light distributor member, and a light detector thereinsubstantially centrally positioned with relation to the narrowtransparent regions.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a top plan view of a typicalembodiment of the present invention.

FIG. 2 is a front view, with portions cut away, of the apparatus shownin FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT document 14 such as a dollarbill or other currency.

Fixedly mounted in a substantially hemispherical recess \l in the lightdistributor member 11 is a source of light 16 such as an incandescentelectric light bulb.

Adjacent each light reception area, such as 17, on the upper surface 13of the document 14, is an opening 18 in the light distributor member 11.Each opening 18 comprises a cylindrical portion 19 and an outwardlyextending conical transparent portion 20 for transmitting light over anillumination area 21 in substantial registry with the light receptionarea 17. Mounted in the cylindrical portion 19 of the opening 18 are alight detector 22, such as a photocell, and a light filter 23.

The light distributor member 11 may be made of any suitable transparentmaterial such as an acrylic resin or plastic. The external surface ofthe light distributor member 11 should be substantially smooth over mostof its area, to contain the light from the source 16 substantiallywithin the member 11 except at the illumination areas 21. A smoothsurface will reflect most of the light impinging upon it at acuteangles, but if it is desired to contain a still larger percentage of thelight Within the member 11 the external surface can be coated with asuitable light reflective material such as aluminum, silver, or beral.Any discontinuities or abrupt changes in the external surface should becoated with light reflective material.

The surface of the cylindrical portion 19 of each opening 18 may becoated with light reflective material to assure that the light detector22 is isolated from all light except that reflected from the adjacentlight reception area 17 on the test surface 13. The surface of theconical portion 20, however, is left uncoated so that it will betransparent and transmit most of the light to the illumination area 21and the adjacent light reception area 17.

Thus the-light from the light source 16 mounted in the recess 15 (whichpreferably, but not necessarily, is substantially centrally located, asshown, among the light reception areas) is transmitted through the lightblock 11 and the transparent conical portion 20 of each opening 18, tothe adjacent illumination area 21 and light reception area 17. Aproportion of the light impinging on the light reception area 17,depending upon the characteristics of the document in that area, isreflected to the light filter 23, which permits a fraction of thereflected light within a preselected frequency range to impinge on thelight detector 22. The light filter 23 may be omitted in some or all ofthe openings 18, where the light detector 23 itself has the desirednarrow band selectivity or where it is desired to detect light over abroad spectrum. Where it may be desired to filter out certain portionsof the spectrum at all areas, the light distributor member 11 may betinted accordingly. As used in this description and in the claims,transparent means having the property of transmitting light over auseful portion of the visible radiation spectrum, but not necessarilyover the entire visible frequency range.

The electrical signals of the light detectors 22 can be measured, ifdesired, to analyze the light reflecting characteristics of the document14. Or they can be used to provide the input to suitable controlcircuits responsive thereto, as in the apparatus of the Wong patent. Anyvariation in the intensity of the light provided by the light source 16affects all of the light detectors 22 proportionally, and thus does notdiminish the accuracy of properly designed measuring or controlcircuits.

Where it is desired to test automatically whether the document 14 iscomplete and properly located, the lower surface 12 of the lightdistributor member 11 may be made to be transparent over a narrow regionwithin the periphery of the test surface 13, as by providing atransparent groove 26 just inside the periphery, and also providingmeans for detecting any light passing through the test surface in thenarrow region of the groove 26.

Suitable means for detecting any light leaking through the test surfacemay include a light reception member 30, comprising a substantiallyrectangular internally trans parent plate similar to the member 11, witha narrow transparent groove 31, in substantial registry with the groove26, just inside the periphery of the upper face 32 of the member 30. Alight detector 33, such as a photocell, may be mounted as shown in acylindrical opening approximately in the center of the lower surface 34of the light reception member 30. The external surface of the lightreception member 30 preferably is coated with reflective material tocontain substantially all light received through the transparent groove31, and to keep out other light. The surfaces of the cylindrical openingholding the light detector 32 should be transparent, at least adjacentto the light sensitive area thereof, to transmit the light to thedetector 33.

While the form of the invention herein disclosed constitutes a preferredembodiment, many others are possible. It is not intended herein tomention all of the possible equivalent forms or ramifications of theinvention. It is to be understood that the terms used herein are merelydescriptive rather than limiting, and that various changes may be madewithout departing from the spirit or scope of the invention.

I claim:

1. Apparatus for providing light of constantly proportional intensitiesin a plurality of light reception areas on a test surface and fordetecting light reflected from said areas comprising in combination:

a solid internally transparent light distributor member having a faceportion adjacent said test surface and comprising an illumination areain substantial registry with each said light reception area,

a recess in said light distributor member having a source of lightfixedly mounted therein, and

an opening in said light distributor member at each said illuminationarea having a light detector positioned therein to receive lightreflected from said test surface.

2. Apparatus as in claim 1, wherein the external surface of said lightdetector member is substantially smooth over most of its area to containthe light from said source substantially within said member except atsaid illumination areas.

3. Apparatus as in claim 2, wherein at least any region of abrupt changein said external surface is coated with light reflective material. 7

4. Apparatus as in claim 1, wherein said recess and light source aresubstantially centrally located among said light reception areas.

5. Apparatus as in claim 1, wherein said light detector member is madeof an acrylic resin.

6. Apparatus as in claim 1, wherein each said opening comprises acylindrical portion for holding said light detector therein and anoutwardly extending conical transparent portion for transmitting lightto said illumination area.

7. Apparatus as in claim 1, wherein each said light dtector is isolatedfrom all light except that reflected from the adjacent light receptionarea on said test surface.

8. Apparatus as in claim 1, wherein each said light detector comprises aphotocell.

9. Apparatus as in claim 1, wherein a light filter is provided in atleast one said opening between said test surface and the light detectorin said opening.

10. Apparatus as in claim 1, wherein said light distributor membertransmits light over a range of frequencies substantially narrower thanthe entire visible spectrum.

11. Apparatus as in claim 10, wherein said light distributor member istinted.

12. Apparatus as in claim 1, wherein said light distributor member istransparent over a narrow region within the periphery of said testsurface, and wherein means are provided for detecting any light passingthrough said References Cited test surface adjacent said narrow region.i UNITED STATES PATENTS 13. Apparatus as 1n claim 12, Wherem saiddetecting A s a means comprises a solid internally transparent light re-3'1221227 2/1964 Bookout at 209*1116 X ception member having a faceportion adjacent said test 3220549 11/1965 Wong 2O9 111'6 5 3,480,78511/1969 Aufderherde 209111.6 X

surface on the side opposite said light distributor member, said faceportion being transparent over a narrow region JAMES W, LAWRENCE,Primary Examiner in substantial registry with said narrow transparentregion of said light distributor member, and a light detector CAMPBELLAsslstam Exammer therein substantially centrally positioned withrelation to 10 U8. Cl. X.R. said narrow transparent regions. 209

